US8353778B2 - Forging method, closed forging mold and tripod uniform motion universal joint - Google Patents

Forging method, closed forging mold and tripod uniform motion universal joint Download PDF

Info

Publication number
US8353778B2
US8353778B2 US13/129,648 US200913129648A US8353778B2 US 8353778 B2 US8353778 B2 US 8353778B2 US 200913129648 A US200913129648 A US 200913129648A US 8353778 B2 US8353778 B2 US 8353778B2
Authority
US
United States
Prior art keywords
surface portion
boss
flat
tapered
respect
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
US13/129,648
Other versions
US20110224004A1 (en
Inventor
Jiahua Miao
Akira Sera
Shunsuke Makino
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NTN Corp
Original Assignee
NTN Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by NTN Corp filed Critical NTN Corp
Assigned to NTN CORPORATION reassignment NTN CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: MAKINO, Shunsuke, MIAO, Jiahua, SERA, AKIRA
Publication of US20110224004A1 publication Critical patent/US20110224004A1/en
Application granted granted Critical
Publication of US8353778B2 publication Critical patent/US8353778B2/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D3/00—Yielding couplings, i.e. with means permitting movement between the connected parts during the drive
    • F16D3/16—Universal joints in which flexibility is produced by means of pivots or sliding or rolling connecting parts
    • F16D3/20—Universal joints in which flexibility is produced by means of pivots or sliding or rolling connecting parts one coupling part entering a sleeve of the other coupling part and connected thereto by sliding or rolling members
    • F16D3/202—Universal joints in which flexibility is produced by means of pivots or sliding or rolling connecting parts one coupling part entering a sleeve of the other coupling part and connected thereto by sliding or rolling members one coupling part having radially projecting pins, e.g. tripod joints
    • F16D3/205—Universal joints in which flexibility is produced by means of pivots or sliding or rolling connecting parts one coupling part entering a sleeve of the other coupling part and connected thereto by sliding or rolling members one coupling part having radially projecting pins, e.g. tripod joints the pins extending radially outwardly from the coupling part
    • F16D3/2055—Universal joints in which flexibility is produced by means of pivots or sliding or rolling connecting parts one coupling part entering a sleeve of the other coupling part and connected thereto by sliding or rolling members one coupling part having radially projecting pins, e.g. tripod joints the pins extending radially outwardly from the coupling part having three pins, i.e. true tripod joints
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
    • B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
    • B21J5/02—Die forging; Trimming by making use of special dies ; Punching during forging
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
    • B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
    • B21J5/02—Die forging; Trimming by making use of special dies ; Punching during forging
    • B21J5/025—Closed die forging
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
    • B21K1/00—Making machine elements
    • B21K1/76—Making machine elements elements not mentioned in one of the preceding groups
    • B21K1/762—Coupling members for conveying mechanical motion, e.g. universal joints
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
    • B21K1/00—Making machine elements
    • B21K1/76—Making machine elements elements not mentioned in one of the preceding groups
    • B21K1/762—Coupling members for conveying mechanical motion, e.g. universal joints
    • B21K1/763—Inner elements of coupling members
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D3/00—Yielding couplings, i.e. with means permitting movement between the connected parts during the drive
    • F16D3/16—Universal joints in which flexibility is produced by means of pivots or sliding or rolling connecting parts
    • F16D3/20—Universal joints in which flexibility is produced by means of pivots or sliding or rolling connecting parts one coupling part entering a sleeve of the other coupling part and connected thereto by sliding or rolling members
    • F16D3/202—Universal joints in which flexibility is produced by means of pivots or sliding or rolling connecting parts one coupling part entering a sleeve of the other coupling part and connected thereto by sliding or rolling members one coupling part having radially projecting pins, e.g. tripod joints
    • F16D2003/2026—Universal joints in which flexibility is produced by means of pivots or sliding or rolling connecting parts one coupling part entering a sleeve of the other coupling part and connected thereto by sliding or rolling members one coupling part having radially projecting pins, e.g. tripod joints with trunnion rings, i.e. with tripod joints having rollers supported by a ring on the trunnion
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2250/00—Manufacturing; Assembly
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2250/00—Manufacturing; Assembly
    • F16D2250/0023—Shaping by pressure

Definitions

  • the present invention relates to a forging method, a full-enclosed forging die, and a tripod type constant velocity universal joint.
  • a full-enclosed forging die In order to form, through full-enclosed forging, a product including a boss portion radially provided with shaft portions, such as a trunnion (tripod member) for constant velocity universal joints and a cross spider for universal joints, a full-enclosed forging die is used.
  • shaft portions such as a trunnion (tripod member) for constant velocity universal joints and a cross spider for universal joints
  • the full-enclosed forging die is described in Patent Literature 1 or the like, and as illustrated in FIG. 7 , includes openable/closable dies 1 and 2 and punches 4 and 5 arranged so as to be operable on a central axis of the dies 1 and 2 .
  • a cavity 9 is formed, which corresponds to shapes of shaft portions 7 and a boss portion 8 of a product 6 .
  • a billet material
  • clamping is performed.
  • the billet is pressed with the punches 4 and 5 so as to be plastically deformed.
  • the product 6 can be formed, which is provided with the boss portion 8 and the shaft portions 7 .
  • an enclosing force is applied so as to maintain the upper and lower dies to be held in contact with each other.
  • a required enclosing force becomes higher in accordance with an increase in size of an object product.
  • the enclosing apparatus is used with a rated enclosing force at an upper limit.
  • use with the rated enclosing force at an upper limit causes a life of the enclosing apparatus to be shortened.
  • an enclosing apparatus capable of applying a desired large enclosing force has to be used.
  • a press machine becomes larger and cost thereof increases.
  • the present invention has been made to provide a forging method and a full-enclosed forging die which contribute to alleviation of the enclosing force applied to the dies and in which a relatively small enclosing apparatus can be used even with respect to larger-sized products. Further, the present invention has been made to provide a tripod type constant velocity universal joint using a tripod member molded with such a full-enclosed forging die.
  • a forging method in which a full-enclosed forging die including openable/closable dies and punches for pressing a material between the openable/closable dies is used so that a product including a boss portion and shaft portions protruded radially from the boss portion is molded, includes making a projection area in a boss-portion axial direction toward a die side of the boss portion smaller than another projection area in the boss-portion axial direction toward the die side, the another projection area being defined when a radially outer surface is formed as a single convex curved surface about a boss-portion axial center.
  • each of the projection area and the another projection area represents an area of a projection portion (area from which an actual area of any one of end surfaces of the boss portion is omitted) on a plane including the any one of the end surfaces, the projection portion being obtained by projection of a boss-portion radially outer portion onto the plane.
  • the projection area can be reduced in the boss-portion axial direction toward the die side of the boss portion, and hence perpendicular (boss-portion axial direction) load which acts on the dies during full enclosure can be reduced.
  • the projection area can be reduced.
  • the tapered-surface portion be a tangent with respect to the convex curved-surface portion.
  • a taper angle of the tapered-surface portion be set to 25° or less.
  • the tapered-surface portion may be a tangent with respect to the concave curved-surface portion.
  • the first flat-surface portion may be a tangent with respect to the convex curved-surface portion, and may be a surface parallel to an axial direction.
  • the second flat-surface portion may be a tangent with respect to the concave curved-surface portion, and may be a surface parallel to the axial direction.
  • a full-enclosed forging die includes openable/closable dies, and punches for pressing a material between the openable/closable dies so that a product including a boss portion and shaft portions protruded radially from the boss portion is molded, in which, in the boss portion of the product to be molded, a projection area in a boss-portion axial direction toward a die side is made to be smaller than another projection area in the boss-portion axial direction toward the die side, the another projection area being defined when a radially outer surface of the boss portion is formed as a single convex curved surface about a boss-portion axial center.
  • the projection area at the time of molding can be reduced in the boss-portion axial direction toward the die side of the boss portion, and hence the perpendicular (boss-portion axial direction) load which acts on the dies during full enclosure can be reduced.
  • a tripod type constant velocity universal joint includes: an outer joint member having an inner peripheral surface provided with three linear track grooves extending in an axial direction; a tripod member arranged in the outer joint member and including three leg shafts protruded radially from a boss portion and a radially outer surface of the boss portion; and torque transmitting elements supported respectively by the three leg shafts and guided respectively by the three linear track grooves, the tripod member being molded with a full-enclosed forging die including openable/closable dies and punches for pressing a material between the openable/closable dies, in which a projection area in a boss-portion axial direction toward a die side of the boss portion of the tripod member is made to be smaller than another projection area in the boss-portion axial direction toward the die side, the another projection area being defined when a radially outer surface is formed as a single convex curved surface about a boss-portion axial center.
  • the perpendicular (boss-portion axial direction) load which acts on the dies during full enclosure can be reduced.
  • the radially outer surface of the boss portion be formed as a surface including a first flat-surface portion, a convex curved-surface portion, a tapered-surface portion, a concave curved-surface portion, and a second flat-surface portion formed in the stated order from an axial central portion.
  • the tapered-surface portion be a tangent with respect to the convex curved-surface portion, and a taper angle of the tapered-surface portion be set to 25° or less.
  • the tapered-surface portion may be a tangent with respect to the concave curved-surface portion.
  • the first flat-surface portion may be a tangent with respect to the convex curved-surface portion, and may be a surface parallel to an axial direction.
  • the second flat-surface portion may be a tangent with respect to the concave curved-surface portion, and may be a surface parallel to the axial direction.
  • each of the torque transmitting elements include: an outer roller inserted into corresponding one of the three linear track grooves of the outer joint member; and an inner roller externally fitted to corresponding one of the three leg shafts so as to be arranged on an inner peripheral side of the outer roller.
  • each of the three leg shafts has such a straight shape as to be orthogonal to an axial line of the tripod type constant velocity universal joint in vertical cross-section, and be held in contact with an inner peripheral surface of the inner roller in a direction orthogonal to the axial line of the tripod type constant velocity universal joint in lateral cross-section.
  • a gap be formed between each of the three leg shafts and the inner peripheral surface of the inner roller.
  • the structure can be obtained, for example, through formation of a lateral sectional shape of each of the three leg shafts into such a substantially elliptical shape as to have a long axis in the direction orthogonal to the axial line of the tripod type constant velocity universal joint.
  • the perpendicular (boss-portion axial direction) load which acts on the dies during full enclosure can be reduced.
  • a small and simple enclosure apparatus apparatus for enclosing dies
  • press-equipment cost can be saved.
  • load on the enclosure apparatus can be alleviated, and hence a life of the enclosure apparatus can be prolonged.
  • the radially outer surface of the boss portion is formed as the surface including the first flat-surface portion, the convex curved-surface portion, the tapered-surface portion, the concave curved-surface portion, and the second flat-surface portion formed in the stated order from the axial central portion.
  • the tripod member is used which is molded with use of the full-enclosed forging die according to the present invention and by the forging method according to the present invention.
  • press-equipment cost of the full-enclosed forging die used for manufacture of the tripod type constant velocity universal joint can be saved.
  • the load on the enclosure apparatus can be alleviated, and hence the life of the enclosure apparatus can be prolonged.
  • each of the three leg shafts through formation of the lateral sectional shape of each of the three leg shafts into such a substantially elliptical shape or the like as to have the long axis in the direction orthogonal to the axial line of the tripod type constant velocity universal joint, the roller and the roller-guide surfaces of each of the three linear track grooves can be effectively avoided from entering an oblique state. As a result, skid resistance during operating-angle driving can be reduced.
  • FIG. 1 A sectional view of a full-enclosed forging die illustrating an embodiment of the present invention.
  • FIG. 2 A main-part outline view of a product molded with the full-enclosed forging die.
  • FIG. 3 A plan view of the product molded with the full-enclosed forging die.
  • FIG. 4 A plan view of the product having a large projection area.
  • FIG. 5 A sectional view of a tripod type constant velocity universal joint using a tripod member molded with the full-enclosed forging die.
  • FIG. 6 A sectional view of a torque transmitting element of the constant velocity universal joint.
  • FIG. 7 A sectional view of a conventional full-enclosed forging die.
  • FIG. 8 A sectional plan view of the conventional full-enclosed forging die.
  • FIG. 1 illustrates a full-enclosed forging die according to the present invention.
  • the full-enclosed forging die includes openable and closable dies 11 and 12 and punches 14 and 15 driven along an opening/closing direction of the dies 11 and 12 so as to press a material in the dies 11 and 12 .
  • the full-enclosed forging die molds a product (for example, a tripod member for constant velocity universal joints) 16 radially provided with shaft portions 17 .
  • the tripod member as the product 16 includes a boss portion 18 and the three shaft portions 17 extending radially outward from the boss portion 18 .
  • Guide holes 21 a and 21 b are provided at respective axial portions of the dies 11 and 12 , and the punches 14 and 15 are fit-inserted respectively into the guide holes 21 a and 21 b . Further, at an opening portion of each of the guide holes 21 a and 21 b on respective mating-surface- 11 a -and- 12 a sides of the dies 11 and 12 , there are respectively arranged three recessed portions 22 and 23 along circumferential directions at pitches of 120° while extending in radial directions.
  • a swelling portion 27 is provided at a central portion of a lower surface 14 a of the upper punch 14
  • a swelling portion 28 is provided at a central portion of an upper surface 15 a of the lower punch 15 .
  • shaft-portion spaces 24 A for forming the shaft portions 17 of the product 16 are formed of the recessed portions 22 and 23 facing each other.
  • a boss-portion space 24 B for molding the boss portion 18 is formed of the punches 14 and 15 and the dies 11 and 12 . That is, a cavity 24 for product molding is constituted by the shaft-portion spaces 24 A and the boss-portion space 24 B.
  • a second flat-surface portion 35 is provided at an axial end portion of the concave curved-surface portion 34 .
  • the first flat-surface portion 31 is a surface parallel to an axial direction, and is a flat surface in a tangential direction with respect to the convex curved-surface portion 32 .
  • the convex curved-surface portion 32 is a curved surface having a curvature center positioned on a radially inner side relative to the radially outer surface 30 .
  • the tapered-surface portion 33 is a flat surface in a tangential direction with respect to the convex curved-surface portion 32 , and is a flat surface in a tangential direction with respect to the concave curved-surface portion 34 .
  • the concave curved-surface portion 34 is a curved surface having a curvature center positioned on a radially outer side relative to the radially outer surface 30 .
  • the second flat-surface portion 35 is a surface parallel to the axial direction, and is a flat surface in a tangential direction with respect to the concave curved-surface portion 34 .
  • a thickness H is set to 28 mm
  • a diameter dimension ⁇ D is set to 44 mm
  • a curvature radius R 1 of the convex curved-surface portion 32 is set to 22 mm
  • a boss-portion-outer-diameter molding surface 40 in the cavity 24 of the full-enclosed forging die there are formed a first flat-surface portion 41 , a convex curved-surface portion 42 , a tapered-surface portion 43 , a concave curved-surface portion 44 , and a second flat-surface portion 45 .
  • the radially outer surface 30 of the boss portion 18 is finished as the surface including the first flat-surface portion 31 , the convex curved-surface portion 32 , the tapered-surface portion 33 , the concave curved-surface portion 34 , and the second flat-surface portion 35 .
  • the upper die 11 and the lower die 12 are brought into such a die-open state as to be separated relatively to each other.
  • the upper punch 14 is raised and the lower punch 15 is lowered.
  • the billet material
  • the billet can be fit-inserted into the guide holes 21 a and 21 b , and corresponds to a volume of a product to be formed.
  • a projection portion 50 in the boss-portion axial direction toward a die side of the boss portion 18 corresponds to a range illustrated by dots (dotted patterns) in FIG. 3 .
  • the projection portion 50 in this case corresponds to a range illustrated by dots (dotted patterns) in FIG. 4 .
  • the projection portion 50 represents a projection portion (part except the end surface 19 or 20 ) obtained by projection of a boss-portion radially outer portion onto a plane (P 1 , P 2 ) including any one of end surfaces 19 ( 20 ) of the boss portion 18 .
  • the projection portion 50 has a radial length A.
  • the projection portion 50 has a radial length A 1 in the boss portion 18 between the shaft portions 17 and 17 adjacent to each other. In this case, A 1 is larger than A.
  • a projection area can be reduced in the boss-portion axial direction toward the die side of the boss portion 18 .
  • the radially outer surface 30 of the boss portion 18 of the product 16 includes the first flat-surface portion 31 , the convex curved-surface portion 32 , the tapered-surface portion 33 , and the concave curved-surface portion 34 .
  • the projection area represents an area of the projection portion (area from which an area of the end surface 19 or 20 of the boss portion 18 is omitted) on the plane P 1 (P 2 ) including any one of the end surfaces 19 ( 20 ), the projection portion being obtained by projection of the boss-portion radially outer portion onto the plane.
  • the projection area can be reduced in the boss-portion axial direction toward the die side of the boss portion 18 , and hence perpendicular (boss-portion axial direction) load which acts on the dies 11 and 12 during full enclosure can be reduced. Accordingly, a small and simple enclosure apparatus (apparatus for enclosing dies) can be used, and hence press-equipment cost can be saved. Further, load on the enclosure apparatus can be alleviated, and hence a life of the enclosure apparatus can be prolonged.
  • the radially outer surface 30 of the boss portion 18 is formed as the surface including the first flat-surface portion 31 , the convex curved-surface portion 32 , the tapered-surface portion 33 , and the concave curved-surface portion 34 formed in the stated order from the axial central portion.
  • the projecting area can be reduced.
  • the perpendicular load which acts on the dies 11 and 12 during full enclosure can be reliably reduced.
  • FIG. 5 illustrates a tripod type constant velocity universal joint using the tripod member 16 molded by a forging method using the full-enclosed forging die according to the present invention.
  • the tripod type constant velocity universal joint includes: an outer joint member 62 having an inner peripheral surface 60 provided with three linear track grooves 61 extending in the axial direction; the tripod member 16 arranged in the outer joint member 62 and including the three leg shafts (shaft portions) 17 protruded radially from the boss portion 18 and the radially outer surface of the boss portion 18 ; and torque transmitting elements 63 supported respectively by the leg shafts 17 and guided respectively by the track grooves 61 .
  • Each of the track grooves 61 has roller-guide surfaces 68 respectively formed on side walls facing each other in a circumferential direction.
  • Each of the torque transmitting elements 63 includes an outer roller 65 inserted into the track groove 61 of the outer joint member 62 and an inner roller 66 externally fitted to the leg shaft 17 so as to be arranged on an inner peripheral side of the outer roller 65 .
  • a plurality of rolling elements 67 are interposed between the outer roller 65 and the inner roller 66 .
  • each the leg shafts 17 has such a straight shape as to be orthogonal to an axial line of the joint in vertical cross-section, and as illustrated in FIG. 6 , is held in contact with an inner peripheral surface of the inner roller 66 in a direction orthogonal to the axial line of the joint in lateral cross-section.
  • a gap is formed between the leg shaft 17 and the inner peripheral surface of the inner roller 66 . That is, in a sectional shape of the leg shaft 17 , surfaces facing each other in the axial direction of the tripod member 16 retract into mutual directions, that is, to a radially inner side relative to an imaginary cylindrical surface.
  • the roller 65 and the roller-guide surfaces 68 can be effectively avoided from entering an oblique state when rotation is made while the outer joint member 62 and the joint inner member (tripod member) 16 form an operating angle. As a result, skid resistance during operating-angle driving can be reduced.
  • the structure can be obtained, for example, through formation of a lateral sectional shape of the leg shaft 17 into such a substantially elliptical shape as to have a long axis in the direction orthogonal to the axial line of the joint.
  • the present invention is not limited to the embodiment described above, and various modifications may be made thereto.
  • the radially outer surface 30 of the boss portion 18 has such a shape as to have the first flat-surface portion 31 , the convex curved-surface portion 32 , the tapered-surface portion 33 , the concave curved-surface portion 34 , and the second flat-surface portion 35 .
  • the present invention is not limited to such a shape. That is, the first flat-surface portion 31 , the tapered-surface portion 33 , the concave curved-surface portion 34 , the second flat-surface portion 35 , and the like may be omitted.
  • the first flat-surface portion 31 it suffices that the convex curved-surface portion 32 is formed up to an axial center of the radially outer surface.
  • the tapered-surface portion 33 it suffices that the convex curved-surface portion 32 is extended up to the concave curved-surface portion 34 .
  • the concave curved-surface portion 34 it suffices that the convex curved-surface portion 32 is extended up to the second flat-surface portion 35 or the tapered-surface portion 33 is extended up to the second flat-surface portion 35 .
  • the dimension of the first flat-surface portion 31 , the curvature radius of the convex curved-surface portion 32 , the taper length L 2 and the taper angle of the tapered-surface portion 33 , the curvature radius of the concave curved-surface portion 34 , the dimension of the second flat-surface portion 35 , and the like may be variously modified as long as the flat-surface portion 31 , the convex curved-surface portion 32 , the tapered-surface portion 33 , the concave curved-surface portion 34 , the second flat-surface portion 35 , and the like are smoothly continuous with each other and the above-mentioned projection area can be reduced.
  • the leg shaft 17 may have a circular sectional shape.
  • the thickness H of the boss portion 18 was set to 28 mm
  • the curvature radius R 1 of the convex curved-surface portion 32 was set to 22 mm
  • the dimension L 1 of the first flat-surface portion 31 was set to 0 mm
  • the dimension L 2 of the tapered-surface portion 33 was set to 12.1 mm at a taper angle of 5°, 8.6 mm at a taper angle of 15°, and 5.2 mm at a taper angle of 25°
  • the curvature radius R 2 of the concave curved-surface portion 34 was set to 0 mm
  • the dimension L 3 of the second flat-surface portion 35 was set to 0 mm.
  • Table 1 shows that, in comparison with a conventional product (as illustrated by the imaginary line in FIG. 2 , the radially outer surface is constituted by the single curved surface about the boss-portion axial center), the enclosing force was successfully reduced by 42% at the taper angle ⁇ of 5°, by 25% at the taper angle ⁇ of 15°, and by 11% at the taper angle ⁇ of 25°. In this manner, when the projection area is reduced in the boss-portion axial direction toward the die side of the boss portion 18 , the enclosing force can be reduced.
  • the present invention is used for a forging method of forming a product including a boss portion radially provided with shaft portions, such as a trunnion (tripod member) for constant velocity universal joints and a cross spider for universal joints.
  • shaft portions such as a trunnion (tripod member) for constant velocity universal joints and a cross spider for universal joints.

Abstract

A forging method and a full-enclosed forging die contribute to the alleviation of an enclosing force applied to dies and in which a relatively small enclosing apparatus can be used even with respect to larger-sized products. A tripod type constant velocity universal joint is formed with a tripod member molded with the full-enclosed forging die. The full-enclosed forging die includes openable/closable dies and punches for pressing a material between the dies. From the forging die, the tripod member including a boss portion and shaft portions protruded radially from the boss portion is molded.

Description

TECHNICAL FIELD
The present invention relates to a forging method, a full-enclosed forging die, and a tripod type constant velocity universal joint.
BACKGROUND ART
In order to form, through full-enclosed forging, a product including a boss portion radially provided with shaft portions, such as a trunnion (tripod member) for constant velocity universal joints and a cross spider for universal joints, a full-enclosed forging die is used.
The full-enclosed forging die is described in Patent Literature 1 or the like, and as illustrated in FIG. 7, includes openable/ closable dies 1 and 2 and punches 4 and 5 arranged so as to be operable on a central axis of the dies 1 and 2. Specifically, through pressing with the punches 4 and 5 under a state in which the dies 1 and 2 are closed, a cavity 9 is formed, which corresponds to shapes of shaft portions 7 and a boss portion 8 of a product 6. Thus, a billet (material) is put into the dies, and then clamping is performed. After that, the billet is pressed with the punches 4 and 5 so as to be plastically deformed. As a result, as illustrated in FIG. 8, the product 6 can be formed, which is provided with the boss portion 8 and the shaft portions 7.
Citation List
Patent Literature
  • [PTL 1] JP 2003-343592 A
SUMMARY OF INVENTION
Technical Problem
In the through full-enclosed forging as described above, with use of an enclosing apparatus using a hydraulic pressure, a spring, or the like, an enclosing force is applied so as to maintain the upper and lower dies to be held in contact with each other. Thus, a required enclosing force becomes higher in accordance with an increase in size of an object product. In some cases, the enclosing apparatus is used with a rated enclosing force at an upper limit. However, use with the rated enclosing force at an upper limit causes a life of the enclosing apparatus to be shortened. Further, in order to mold a larger-sized product requiring a higher enclosing force, an enclosing apparatus capable of applying a desired large enclosing force has to be used. In accordance therewith, a press machine becomes larger and cost thereof increases.
In view of the above-mentioned problems, the present invention has been made to provide a forging method and a full-enclosed forging die which contribute to alleviation of the enclosing force applied to the dies and in which a relatively small enclosing apparatus can be used even with respect to larger-sized products. Further, the present invention has been made to provide a tripod type constant velocity universal joint using a tripod member molded with such a full-enclosed forging die.
Solution to Problem
A forging method according to the present invention, in which a full-enclosed forging die including openable/closable dies and punches for pressing a material between the openable/closable dies is used so that a product including a boss portion and shaft portions protruded radially from the boss portion is molded, includes making a projection area in a boss-portion axial direction toward a die side of the boss portion smaller than another projection area in the boss-portion axial direction toward the die side, the another projection area being defined when a radially outer surface is formed as a single convex curved surface about a boss-portion axial center. In this case, each of the projection area and the another projection area represents an area of a projection portion (area from which an actual area of any one of end surfaces of the boss portion is omitted) on a plane including the any one of the end surfaces, the projection portion being obtained by projection of a boss-portion radially outer portion onto the plane.
According to the forging method of the present invention, the projection area can be reduced in the boss-portion axial direction toward the die side of the boss portion, and hence perpendicular (boss-portion axial direction) load which acts on the dies during full enclosure can be reduced.
By forming the radially outer surface of the boss portion as a surface including a first flat-surface portion, a convex curved-surface portion, a tapered-surface portion, a concave curved-surface portion, and a second flat-surface portion formed in the stated order from an axial central portion, the projection area can be reduced. In this case, it is preferred that the tapered-surface portion be a tangent with respect to the convex curved-surface portion. Further, it is preferred that a taper angle of the tapered-surface portion be set to 25° or less. In addition, the tapered-surface portion may be a tangent with respect to the concave curved-surface portion. The first flat-surface portion may be a tangent with respect to the convex curved-surface portion, and may be a surface parallel to an axial direction. The second flat-surface portion may be a tangent with respect to the concave curved-surface portion, and may be a surface parallel to the axial direction.
A full-enclosed forging die according to the present invention includes openable/closable dies, and punches for pressing a material between the openable/closable dies so that a product including a boss portion and shaft portions protruded radially from the boss portion is molded, in which, in the boss portion of the product to be molded, a projection area in a boss-portion axial direction toward a die side is made to be smaller than another projection area in the boss-portion axial direction toward the die side, the another projection area being defined when a radially outer surface of the boss portion is formed as a single convex curved surface about a boss-portion axial center.
According to the full-enclosed forging die of the present invention, the projection area at the time of molding can be reduced in the boss-portion axial direction toward the die side of the boss portion, and hence the perpendicular (boss-portion axial direction) load which acts on the dies during full enclosure can be reduced.
A tripod type constant velocity universal joint according to the present invention includes: an outer joint member having an inner peripheral surface provided with three linear track grooves extending in an axial direction; a tripod member arranged in the outer joint member and including three leg shafts protruded radially from a boss portion and a radially outer surface of the boss portion; and torque transmitting elements supported respectively by the three leg shafts and guided respectively by the three linear track grooves, the tripod member being molded with a full-enclosed forging die including openable/closable dies and punches for pressing a material between the openable/closable dies, in which a projection area in a boss-portion axial direction toward a die side of the boss portion of the tripod member is made to be smaller than another projection area in the boss-portion axial direction toward the die side, the another projection area being defined when a radially outer surface is formed as a single convex curved surface about a boss-portion axial center.
According to the tripod type constant velocity universal joint of the present invention, in the dies of the full-enclosed forging die used at the time of molding of the tripod member, the perpendicular (boss-portion axial direction) load which acts on the dies during full enclosure can be reduced.
It is preferred that the radially outer surface of the boss portion be formed as a surface including a first flat-surface portion, a convex curved-surface portion, a tapered-surface portion, a concave curved-surface portion, and a second flat-surface portion formed in the stated order from an axial central portion. Further, it is preferred that the tapered-surface portion be a tangent with respect to the convex curved-surface portion, and a taper angle of the tapered-surface portion be set to 25° or less. In addition, the tapered-surface portion may be a tangent with respect to the concave curved-surface portion. The first flat-surface portion may be a tangent with respect to the convex curved-surface portion, and may be a surface parallel to an axial direction. The second flat-surface portion may be a tangent with respect to the concave curved-surface portion, and may be a surface parallel to the axial direction.
It is preferred that each of the torque transmitting elements include: an outer roller inserted into corresponding one of the three linear track grooves of the outer joint member; and an inner roller externally fitted to corresponding one of the three leg shafts so as to be arranged on an inner peripheral side of the outer roller. Further, it is preferred that each of the three leg shafts has such a straight shape as to be orthogonal to an axial line of the tripod type constant velocity universal joint in vertical cross-section, and be held in contact with an inner peripheral surface of the inner roller in a direction orthogonal to the axial line of the tripod type constant velocity universal joint in lateral cross-section. Further, it is preferred that, in an axial-line direction of the tripod type constant velocity universal joint, a gap be formed between each of the three leg shafts and the inner peripheral surface of the inner roller.
With this structure, without loss of torque transmitting property, when rotation is made while the outer joint member and the joint inner member (tripod member) form an operating angle, the roller and the roller-guide surfaces can be more effectively avoided from entering an oblique state. Note that, the structure can be obtained, for example, through formation of a lateral sectional shape of each of the three leg shafts into such a substantially elliptical shape as to have a long axis in the direction orthogonal to the axial line of the tripod type constant velocity universal joint.
Advantageous Effects of Invention
In the present invention, the perpendicular (boss-portion axial direction) load which acts on the dies during full enclosure can be reduced. With this, a small and simple enclosure apparatus (apparatus for enclosing dies) can be used, and hence press-equipment cost can be saved. Further, load on the enclosure apparatus can be alleviated, and hence a life of the enclosure apparatus can be prolonged.
The radially outer surface of the boss portion is formed as the surface including the first flat-surface portion, the convex curved-surface portion, the tapered-surface portion, the concave curved-surface portion, and the second flat-surface portion formed in the stated order from the axial central portion. Thus, the above-mentioned projection area can be reduced. Thus, the perpendicular load which acts on the dies during full enclosure can be reliably reduced.
Further, in the tripod type constant velocity universal joint according to the present invention, the tripod member is used which is molded with use of the full-enclosed forging die according to the present invention and by the forging method according to the present invention. Thus, press-equipment cost of the full-enclosed forging die used for manufacture of the tripod type constant velocity universal joint can be saved. Further, the load on the enclosure apparatus can be alleviated, and hence the life of the enclosure apparatus can be prolonged.
In addition, through formation of the lateral sectional shape of each of the three leg shafts into such a substantially elliptical shape or the like as to have the long axis in the direction orthogonal to the axial line of the tripod type constant velocity universal joint, the roller and the roller-guide surfaces of each of the three linear track grooves can be effectively avoided from entering an oblique state. As a result, skid resistance during operating-angle driving can be reduced. Thus, in vehicles using such constant velocity universal joints, it is possible to suppress phenomena such as vehicle-body vibration and noise which are caused by an increase in friction, and hence to maintain stable vibration property of the vehicles.
BRIEF DESCRIPTION OF DRAWINGS
[FIG. 1] A sectional view of a full-enclosed forging die illustrating an embodiment of the present invention.
[FIG. 2] A main-part outline view of a product molded with the full-enclosed forging die.
[FIG. 3] A plan view of the product molded with the full-enclosed forging die.
[FIG. 4] A plan view of the product having a large projection area.
[FIG. 5] A sectional view of a tripod type constant velocity universal joint using a tripod member molded with the full-enclosed forging die.
[FIG. 6] A sectional view of a torque transmitting element of the constant velocity universal joint.
[FIG. 7] A sectional view of a conventional full-enclosed forging die.
[FIG. 8] A sectional plan view of the conventional full-enclosed forging die.
 DETAILED DESCRIPTION OF THE INVENTION
In the following, description is made of an embodiment of the present invention with reference to FIGS. 1 to 8.
FIG. 1 illustrates a full-enclosed forging die according to the present invention. The full-enclosed forging die includes openable and closable dies 11 and 12 and punches 14 and 15 driven along an opening/closing direction of the dies 11 and 12 so as to press a material in the dies 11 and 12. The full-enclosed forging die molds a product (for example, a tripod member for constant velocity universal joints) 16 radially provided with shaft portions 17. Note that, the tripod member as the product 16 includes a boss portion 18 and the three shaft portions 17 extending radially outward from the boss portion 18.
Guide holes 21 a and 21 b are provided at respective axial portions of the dies 11 and 12, and the punches 14 and 15 are fit-inserted respectively into the guide holes 21 a and 21 b. Further, at an opening portion of each of the guide holes 21 a and 21 b on respective mating-surface-11 a-and-12 a sides of the dies 11 and 12, there are respectively arranged three recessed portions 22 and 23 along circumferential directions at pitches of 120° while extending in radial directions.
Still further, a swelling portion 27 is provided at a central portion of a lower surface 14 a of the upper punch 14, and a swelling portion 28 is provided at a central portion of an upper surface 15 a of the lower punch 15.
Under a state in which the dies 11 and 12 are superimposed on each other as illustrated in FIG. 1, shaft-portion spaces 24A for forming the shaft portions 17 of the product 16 are formed of the recessed portions 22 and 23 facing each other. Further, a boss-portion space 24B for molding the boss portion 18 is formed of the punches 14 and 15 and the dies 11 and 12. That is, a cavity 24 for product molding is constituted by the shaft-portion spaces 24A and the boss-portion space 24B.
By the way, as illustrated in FIG. 2, on a radially outer surface 30 of the boss portion 18 of the product 16, there is formed a surface including a first flat-surface portion 31, a convex curved-surface portion 32, a tapered-surface portion 33, and a concave curved-surface portion 34 in the stated order from an axial central portion. In addition, a second flat-surface portion 35 is provided at an axial end portion of the concave curved-surface portion 34.
In this case, the first flat-surface portion 31 is a surface parallel to an axial direction, and is a flat surface in a tangential direction with respect to the convex curved-surface portion 32. The convex curved-surface portion 32 is a curved surface having a curvature center positioned on a radially inner side relative to the radially outer surface 30. The tapered-surface portion 33 is a flat surface in a tangential direction with respect to the convex curved-surface portion 32, and is a flat surface in a tangential direction with respect to the concave curved-surface portion 34. The concave curved-surface portion 34 is a curved surface having a curvature center positioned on a radially outer side relative to the radially outer surface 30. The second flat-surface portion 35 is a surface parallel to the axial direction, and is a flat surface in a tangential direction with respect to the concave curved-surface portion 34.
For example, in the boss portion 18, when a thickness H is set to 28 mm, a diameter dimension ØD is set to 44 mm, and a curvature radius R1 of the convex curved-surface portion 32 is set to 22 mm, it is possible to set a dimension L1 of the first flat-surface portion 31 to 1 mm, a taper angle α of the tapered-surface portion 33 to 25° , a dimension L2 of the tapered-surface portion 33 to 2 mm, a curvature radius R2 of the concave curved-surface portion 34 to 3 mm, and a dimension L3 of the second flat-surface portion 35 to 0.6 mm.
In other words, as illustrated in FIG. 1, on a boss-portion-outer-diameter molding surface 40 in the cavity 24 of the full-enclosed forging die, there are formed a first flat-surface portion 41, a convex curved-surface portion 42, a tapered-surface portion 43, a concave curved-surface portion 44, and a second flat-surface portion 45. At the time of molding, the radially outer surface 30 of the boss portion 18 is finished as the surface including the first flat-surface portion 31, the convex curved-surface portion 32, the tapered-surface portion 33, the concave curved-surface portion 34, and the second flat-surface portion 35.
Next, description is made of a forging method with use of the above-mentioned die. First, the upper die 11 and the lower die 12 are brought into such a die-open state as to be separated relatively to each other. In this case, the upper punch 14 is raised and the lower punch 15 is lowered. In this state, the billet (material) is put into the guide hole 21 b of the lower die 12. Note that, the billet can be fit-inserted into the guide holes 21 a and 21 b, and corresponds to a volume of a product to be formed.
After that, clamping is performed so as to bring the upper die 11 and the lower die 12 close relatively to each other. Next, the upper punch 14 is lowered, and simultaneously the lower punch 15 is raised. With this, the above-mentioned spaces 24A are formed in which the billet is pressed from above and below so that the shaft portions 17 are formed. A part of the billet is fluidized in the spaces 24A so that the product 16 (tripod member) including the three shaft portions 17 radially around the boss portion 18 is formed.
By the way, a projection portion 50 in the boss-portion axial direction toward a die side of the boss portion 18 corresponds to a range illustrated by dots (dotted patterns) in FIG. 3. Meanwhile, when the radially outer surface of the boss portion 18 is formed as a single convex curved surface 51 (curved surface illustrated by an imaginary line in FIG. 2) about a boss-portion axial center, the projection portion 50 in this case corresponds to a range illustrated by dots (dotted patterns) in FIG. 4. Here, the projection portion 50 represents a projection portion (part except the end surface 19 or 20) obtained by projection of a boss-portion radially outer portion onto a plane (P1, P2) including any one of end surfaces 19 (20) of the boss portion 18.
In comparison between FIGS. 3 and 4, in FIG. 3, in the boss portion 18 between the shaft portions 17 and 17 adjacent to each other, the projection portion 50 has a radial length A. In FIG. 4, in the boss portion 18 between the shaft portions 17 and 17 adjacent to each other, the projection portion 50 has a radial length A1. In this case, A1 is larger than A.
In other words, in the present invention, as illustrated in FIG. 3, a projection area can be reduced in the boss-portion axial direction toward the die side of the boss portion 18. This is because, as described above, the radially outer surface 30 of the boss portion 18 of the product 16 includes the first flat-surface portion 31, the convex curved-surface portion 32, the tapered-surface portion 33, and the concave curved-surface portion 34. The projection area represents an area of the projection portion (area from which an area of the end surface 19 or 20 of the boss portion 18 is omitted) on the plane P1 (P2) including any one of the end surfaces 19 (20), the projection portion being obtained by projection of the boss-portion radially outer portion onto the plane.
In the present invention, the projection area can be reduced in the boss-portion axial direction toward the die side of the boss portion 18, and hence perpendicular (boss-portion axial direction) load which acts on the dies 11 and 12 during full enclosure can be reduced. Accordingly, a small and simple enclosure apparatus (apparatus for enclosing dies) can be used, and hence press-equipment cost can be saved. Further, load on the enclosure apparatus can be alleviated, and hence a life of the enclosure apparatus can be prolonged.
The radially outer surface 30 of the boss portion 18 is formed as the surface including the first flat-surface portion 31, the convex curved-surface portion 32, the tapered-surface portion 33, and the concave curved-surface portion 34 formed in the stated order from the axial central portion. Thus, the projecting area can be reduced. Thus, the perpendicular load which acts on the dies 11 and 12 during full enclosure can be reliably reduced.
FIG. 5 illustrates a tripod type constant velocity universal joint using the tripod member 16 molded by a forging method using the full-enclosed forging die according to the present invention. The tripod type constant velocity universal joint includes: an outer joint member 62 having an inner peripheral surface 60 provided with three linear track grooves 61 extending in the axial direction; the tripod member 16 arranged in the outer joint member 62 and including the three leg shafts (shaft portions) 17 protruded radially from the boss portion 18 and the radially outer surface of the boss portion 18; and torque transmitting elements 63 supported respectively by the leg shafts 17 and guided respectively by the track grooves 61. Each of the track grooves 61 has roller-guide surfaces 68 respectively formed on side walls facing each other in a circumferential direction.
Each of the torque transmitting elements 63 includes an outer roller 65 inserted into the track groove 61 of the outer joint member 62 and an inner roller 66 externally fitted to the leg shaft 17 so as to be arranged on an inner peripheral side of the outer roller 65. In this case, a plurality of rolling elements 67 are interposed between the outer roller 65 and the inner roller 66.
Further, each the leg shafts 17 has such a straight shape as to be orthogonal to an axial line of the joint in vertical cross-section, and as illustrated in FIG. 6, is held in contact with an inner peripheral surface of the inner roller 66 in a direction orthogonal to the axial line of the joint in lateral cross-section. In addition, in the axial direction of the joint, a gap is formed between the leg shaft 17 and the inner peripheral surface of the inner roller 66. That is, in a sectional shape of the leg shaft 17, surfaces facing each other in the axial direction of the tripod member 16 retract into mutual directions, that is, to a radially inner side relative to an imaginary cylindrical surface.
With this structure, without loss of torque transmitting property, the roller 65 and the roller-guide surfaces 68 can be effectively avoided from entering an oblique state when rotation is made while the outer joint member 62 and the joint inner member (tripod member) 16 form an operating angle. As a result, skid resistance during operating-angle driving can be reduced. Thus, in vehicles using such constant velocity universal joints, it is possible to suppress phenomena such as vehicle-body vibration and noise which are caused by an increase in friction, and hence to maintain stable vibration property of the vehicles. Note that, the structure can be obtained, for example, through formation of a lateral sectional shape of the leg shaft 17 into such a substantially elliptical shape as to have a long axis in the direction orthogonal to the axial line of the joint.
Hereinabove, although description is made of the embodiment of the present invention, the present invention is not limited to the embodiment described above, and various modifications may be made thereto. For example, in the embodiment described above, the radially outer surface 30 of the boss portion 18 has such a shape as to have the first flat-surface portion 31, the convex curved-surface portion 32, the tapered-surface portion 33, the concave curved-surface portion 34, and the second flat-surface portion 35. However, the present invention is not limited to such a shape. That is, the first flat-surface portion 31, the tapered-surface portion 33, the concave curved-surface portion 34, the second flat-surface portion 35, and the like may be omitted. In this case, it is possible to omit only one of, all of, or arbitrary two of the first flat-surface portion 31, the tapered-surface portion 33, the concave curved-surface portion 34, and the second flat-surface portion 35. When the first flat-surface portion 31 is omitted, it suffices that the convex curved-surface portion 32 is formed up to an axial center of the radially outer surface. When the tapered-surface portion 33 is omitted, it suffices that the convex curved-surface portion 32 is extended up to the concave curved-surface portion 34. When the concave curved-surface portion 34 is omitted, it suffices that the convex curved-surface portion 32 is extended up to the second flat-surface portion 35 or the tapered-surface portion 33 is extended up to the second flat-surface portion 35.
Further, the dimension of the first flat-surface portion 31, the curvature radius of the convex curved-surface portion 32, the taper length L2 and the taper angle of the tapered-surface portion 33, the curvature radius of the concave curved-surface portion 34, the dimension of the second flat-surface portion 35, and the like may be variously modified as long as the flat-surface portion 31, the convex curved-surface portion 32, the tapered-surface portion 33, the concave curved-surface portion 34, the second flat-surface portion 35, and the like are smoothly continuous with each other and the above-mentioned projection area can be reduced. Still further, the leg shaft 17 may have a circular sectional shape.
EXAMPLE 1
Next, an examination was made on an enclosing force applied on the dies 11 and 12 of the full-enclosed forging die, and Table 1 below shows the results of the examination. In Table 1, “taper angle” represents the taper angle of the tapered-surface portion 33. Further, the thickness H of the boss portion 18 was set to 28 mm, the curvature radius R1 of the convex curved-surface portion 32 was set to 22 mm, the dimension L1 of the first flat-surface portion 31 was set to 0 mm, the dimension L2 of the tapered-surface portion 33 was set to 12.1 mm at a taper angle of 5°, 8.6 mm at a taper angle of 15°, and 5.2 mm at a taper angle of 25°, the curvature radius R2 of the concave curved-surface portion 34 was set to 0 mm, and the dimension L3 of the second flat-surface portion 35 was set to 0 mm.
TABLE 1
Taper angle ∠α Enclosing force
 5° 42%
15° 25%
25° 11%
Table 1 shows that, in comparison with a conventional product (as illustrated by the imaginary line in FIG. 2, the radially outer surface is constituted by the single curved surface about the boss-portion axial center), the enclosing force was successfully reduced by 42% at the taper angle α of 5°, by 25% at the taper angle α of 15°, and by 11% at the taper angle α of 25°. In this manner, when the projection area is reduced in the boss-portion axial direction toward the die side of the boss portion 18, the enclosing force can be reduced.
Industrial Applicability
The present invention is used for a forging method of forming a product including a boss portion radially provided with shaft portions, such as a trunnion (tripod member) for constant velocity universal joints and a cross spider for universal joints.
REFERENCE SIGNS LIST
11, 12 die
14, 15 punch
16 product (tripod member)
17 shaft portion (leg shaft)
18 boss portion
24 cavity
30 radially outer surface
31 flat-surface portion
32 convex curved-surface portion
33 tapered-surface portion
34 concave curved-surface portion
60 inner peripheral surface
61 track groove
62 outer joint member
63 torque transmitting element
65 outer roller
66 inner roller

Claims (5)

1. A tripod type constant velocity universal joint comprising:
an outer joint member having an inner peripheral surface provided with three linear track grooves extending in an axial direction;
a tripod member arranged in the outer joint member and including a boss portion and three leg shafts protruding from a radially outer surface of the boss portion; and
a plurality of torque transmitting elements supported respectively by the three leg shafts and guided respectively by the three linear track grooves, the tripod member being molded with a full-enclosed forging die including a plurality of openable/closable dies and a plurality of punches for pressing a material between the openable/closable dies,
wherein the radially outer surface of the boss portion of the tripod member comprises, from an axial central portion to each of opposite end surfaces, a first flat-surface portion, a convex curved-surface portion, a tapered-surface portion, a concave curved-surface portion, and a second flat-surface portion, the tapered-surface portion being tangential with respect to the convex curved-surface portion, a taper angle of the tapered-surface portion being set to 25° or less, the tapered-surface portion being tangential with respect to the concave curved-surface portion, the first flat-surface portion being tangential with respect to the convex curved-surface portion and being parallel to an axial direction, and the second flat-surface portion being tangential with respect to the concave curved-surface portion and being parallel to the axial direction, and
wherein a projection area of an entire periphery in a peripheral direction of a projection portion of the radially outer surface of the boss portion on a plane including either of the opposite end surfaces of the boss portion is smaller than if the radially outer surface was formed as a single convex curved surface about a boss-portion axial center.
2. A tripod type constant velocity universal joint according to claim 1,
wherein each of the torque transmitting elements comprises:
an outer roller inserted into a corresponding one of the three linear track grooves of the outer joint member; and
an inner roller externally fitted to a corresponding one of the three leg shafts so as to be arranged on an inner peripheral side of the outer roller,
wherein each of the three leg shafts has a straight shape so as to be orthogonal to an axial line of the tripod type constant velocity universal joint in vertical cross-section, and is held in contact with an inner peripheral surface of the respective inner roller in a direction orthogonal to the axial line of the tripod type constant velocity universal joint in lateral cross-section, and
wherein, in an axial-line direction of the tripod type constant velocity universal joint, a gap is formed between each of the three leg shafts and the inner peripheral surface of the respective inner roller.
3. A tripod type constant velocity universal joint according to claim 2, wherein a lateral sectional shape of each of the three leg shafts is a substantially elliptical shape.
4. A forging method for forming a product with a full-enclosed forging die including a plurality of openable/closable dies and a plurality of punches for pressing a material between the openable/closable dies, the forging method comprising:
pressing the material between the openable/closable dies with the punches to mold the product including a boss portion and a plurality of shaft portions protruding radially from the boss portion,
wherein a radially outer surface of the boss portion comprises, from an axial central portion to each of opposite end surfaces, a first flat-surface portion, a convex curved-surface portion, a tapered-surface portion, a concave curved-surface portion, and a second flat-surface portion, the tapered-surface portion being tangential with respect to the convex curved-surface portion, a taper angle of the tapered-surface portion being set to 25° or less, the tapered-surface portion being tangential with respect to the concave curved-surface portion, the first flat-surface portion being tangential with respect to the convex curved-surface portion and being parallel to an axial direction, and the second flat-surface portion being tangential with respect to the concave curved-surface portion and being parallel to the axial direction, and
wherein a projection area of an entire periphery in a peripheral direction of a projection portion of the radially outer surface of the boss portion on a plane including either of the opposite end surfaces of the boss portion is smaller than if the radially outer surface was formed as a single convex curved surface about a boss-portion axial center.
5. A full-enclosed die comprising:
a plurality of openable/closable dies; and
a plurality of punches for pressing a material between the openable/closable dies so that a product including a boss portion and a plurality of shaft portions protruding radially from the boss portion is molded,
wherein, in the boss portion of the product, a radially outer surface of the boss portion comprises, from an axial central portion to each of opposite end surfaces, a first flat-surface portion, a convex curved-surface portion, a tapered-surface portion, a concave curved-surface portion, and a second flat-surface portion, the tapered-surface portion being tangential with respect to the convex curved-surface portion, a taper angle of the tapered-surface portion being set to 25° or less, the tapered-surface portion being tangential with respect to the concave curved-surface portion, the first flat-surface portion being tangential with respect to the convex curved-surface portion and being parallel to an axial direction, and the second flat-surface portion being tangential with respect to the concave curved-surface portion and being parallel to the axial direction, and
wherein a projection area of an entire periphery in a peripheral direction of a projection portion of the radially outer surface of the boss portion on a plane including either of the opposite end surfaces of the boss portion is smaller than if the radially outer surface was formed as a single convex curved surface about a boss-portion axial center.
US13/129,648 2008-12-22 2009-11-30 Forging method, closed forging mold and tripod uniform motion universal joint Active US8353778B2 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2008325943A JP5253991B2 (en) 2008-12-22 2008-12-22 Forging method, closed forging die, and tripod type constant velocity universal joint
JP2008-325943 2008-12-22
PCT/JP2009/070104 WO2010073877A1 (en) 2008-12-22 2009-11-30 Forging method, closed forging mold and tripod uniform motion universal joint

Publications (2)

Publication Number Publication Date
US20110224004A1 US20110224004A1 (en) 2011-09-15
US8353778B2 true US8353778B2 (en) 2013-01-15

Family

ID=42287495

Family Applications (1)

Application Number Title Priority Date Filing Date
US13/129,648 Active US8353778B2 (en) 2008-12-22 2009-11-30 Forging method, closed forging mold and tripod uniform motion universal joint

Country Status (5)

Country Link
US (1) US8353778B2 (en)
EP (1) EP2388083B1 (en)
JP (1) JP5253991B2 (en)
CN (1) CN102256722B (en)
WO (1) WO2010073877A1 (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI587943B (en) * 2015-01-23 2017-06-21 chuan-rong Lai Universal joint universal joint forming method and device
CN108380687A (en) * 2018-01-12 2018-08-10 江苏理研科技股份有限公司 A kind of closed type extrusion molding dies that bulb three is sold
CN111141234B (en) * 2018-03-01 2021-06-04 杭州富阳新远新能源有限公司 Ball seat painting area for automobile ball hinge joint and partition detection method thereof
CN114905769B (en) * 2022-07-19 2022-10-25 成都泰格尔航天航空科技股份有限公司 Fabric honeycomb forming device and fabric honeycomb forming process

Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0169091A1 (en) * 1984-06-21 1986-01-22 Automobiles Peugeot Sliding universal joints
EP0296025A1 (en) * 1987-06-12 1988-12-21 Automobiles Peugeot Transmission device with a tubular shaft
GB2226102A (en) * 1988-12-17 1990-06-20 Spicer Hardy Ltd Constant velocity ratio universal joint of the tripod type
US4971595A (en) * 1987-07-01 1990-11-20 Honda Giken Kogyo Kabushiki Kaisha Sliding universal joint having a holder inclination restriction flange and independent rails
JPH0791457A (en) * 1990-04-18 1995-04-04 Glaenzer Spicer Sa Sliding type transmission joint
US6298556B1 (en) * 1992-11-28 2001-10-09 Gkn Automotive Gmbh Connection between inner joint part and driveshaft
JP2003343592A (en) 2002-05-28 2003-12-03 Toyota Motor Corp Tripod assembly and cold closed forging method of shaped tripod
US20040048676A1 (en) * 2002-09-05 2004-03-11 Ntn Corporation Rolling bearing ring of constant velocity joint, and support component for rolling and swinging motion
JP2006183725A (en) 2004-12-27 2006-07-13 Toyota Motor Corp Cvj tripod and its manufacturing method and equipment
US7217194B2 (en) * 2003-08-04 2007-05-15 Ntn Corporation Constant velocity universal joint
US20080184765A1 (en) * 2007-02-02 2008-08-07 Miao Jiahua Closed forging die and forging method
WO2008117612A1 (en) 2007-03-26 2008-10-02 Ntn Corporation Trunnion, toripod-type constant-velocity universal joint using the trunnion and method of producing the same
US7922590B2 (en) * 2007-11-12 2011-04-12 Gkn Driveline North America, Inc. Grease reduction insert

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH03146237A (en) * 1989-11-02 1991-06-21 Honda Motor Co Ltd Production of spider for synchronous joint
JP3599618B2 (en) * 1999-03-05 2004-12-08 Ｎｔｎ株式会社 Constant velocity universal joint

Patent Citations (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0169091A1 (en) * 1984-06-21 1986-01-22 Automobiles Peugeot Sliding universal joints
EP0296025A1 (en) * 1987-06-12 1988-12-21 Automobiles Peugeot Transmission device with a tubular shaft
US4971595A (en) * 1987-07-01 1990-11-20 Honda Giken Kogyo Kabushiki Kaisha Sliding universal joint having a holder inclination restriction flange and independent rails
GB2226102A (en) * 1988-12-17 1990-06-20 Spicer Hardy Ltd Constant velocity ratio universal joint of the tripod type
JPH0791457A (en) * 1990-04-18 1995-04-04 Glaenzer Spicer Sa Sliding type transmission joint
US6298556B1 (en) * 1992-11-28 2001-10-09 Gkn Automotive Gmbh Connection between inner joint part and driveshaft
JP2003343592A (en) 2002-05-28 2003-12-03 Toyota Motor Corp Tripod assembly and cold closed forging method of shaped tripod
US20040048676A1 (en) * 2002-09-05 2004-03-11 Ntn Corporation Rolling bearing ring of constant velocity joint, and support component for rolling and swinging motion
US7217194B2 (en) * 2003-08-04 2007-05-15 Ntn Corporation Constant velocity universal joint
JP2006183725A (en) 2004-12-27 2006-07-13 Toyota Motor Corp Cvj tripod and its manufacturing method and equipment
US20080184765A1 (en) * 2007-02-02 2008-08-07 Miao Jiahua Closed forging die and forging method
WO2008117612A1 (en) 2007-03-26 2008-10-02 Ntn Corporation Trunnion, toripod-type constant-velocity universal joint using the trunnion and method of producing the same
JP2008240825A (en) 2007-03-26 2008-10-09 Ntn Corp Machining method, trunnion and tripod type constant velocity universal joint
EP2141375A1 (en) 2007-03-26 2010-01-06 NTN Corporation Trunnion, toripod-type constant-velocity universal joint using the trunnion and method of producing the same
US7922590B2 (en) * 2007-11-12 2011-04-12 Gkn Driveline North America, Inc. Grease reduction insert

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
International Preliminary Report on Patentability and Written Opinion of the International Searching Authority issued Jul. 14, 2011 in International (PCT) Application No. PCT/JP2009/070104.
International Search Report issued Jan. 12, 2010 in International (PCT) Application No. PCT/JP2009/070104.

Also Published As

Publication number Publication date
EP2388083A4 (en) 2016-03-02
CN102256722B (en) 2013-10-23
EP2388083A1 (en) 2011-11-23
US20110224004A1 (en) 2011-09-15
WO2010073877A1 (en) 2010-07-01
CN102256722A (en) 2011-11-23
EP2388083B1 (en) 2019-05-15
JP5253991B2 (en) 2013-07-31
JP2010142868A (en) 2010-07-01

Similar Documents

Publication Publication Date Title
US8353778B2 (en) Forging method, closed forging mold and tripod uniform motion universal joint
US9132473B2 (en) Forging method, molding device for forgings, and tripod uniform motion universal joint
JP2019520535A (en) Method of manufacturing cage for constant velocity ball joint
JP3836331B2 (en) Method for manufacturing constant velocity universal joint outer ring
US20110130211A1 (en) Tripod-type constant-velocity universal joint and method of manufacturing the same
US20120283059A1 (en) Elements of vehicular continuously variable transmission belt, and method of manufacturing the elements
WO2015146879A1 (en) Closed forging method for universal joint trunnion and universal joint trunnion
KR101578319B1 (en) Ribbon cage and method for manufacturing same
US2431764A (en) Chain construction
JP2006142363A (en) Method for manufacturing brake disk
JP3862429B2 (en) Method and apparatus for manufacturing inner ring for constant velocity joint
JP4467071B2 (en) Powder mold equipment
US10525522B2 (en) Molding device for manufacturing cylindrical rolling body, manufacturing method for cylindrical rolling body, manufacturing method for rolling bearing, manufacturing method for vehicle, and manufacturing method for mechanical apparatus
JP6342365B2 (en) Roll forming equipment
JPS608128B2 (en) Manufacturing method of universal joint yoke
JP2013151005A (en) Method and device for producing bottomed cylindrical member
CN102483128B (en) Method For Manufacturing A Transverse Element Which Is Destined To Be Part Of A Push Belt For A Continuously Variable Transmission
JP3690466B2 (en) Manufacturing method of outer ring member in constant velocity universal shaft joint
JP6366364B2 (en) Wheel
JP2002045942A (en) Method for forming disk-like stock
JP2023149445A (en) Square can manufacturing method and square can manufacturing device
JP5573211B2 (en) Manufacturing method of outer ring of sliding type constant velocity joint and sliding type constant velocity joint
JP2014155954A (en) Die for powder molding
WO2017033656A1 (en) Roll forming method for metal material and roll forming device for metal material
JP2011094685A (en) Method for manufacturing element for vehicular transmission belt

Legal Events

Date Code Title Description
AS Assignment

Owner name: NTN CORPORATION, JAPAN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:MIAO, JIAHUA;SERA, AKIRA;MAKINO, SHUNSUKE;REEL/FRAME:026292/0178

Effective date: 20110426

STCF Information on status: patent grant

Free format text: PATENTED CASE

FPAY Fee payment

Year of fee payment: 4

MAFP Maintenance fee payment

Free format text: PAYMENT OF MAINTENANCE FEE, 8TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1552); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

Year of fee payment: 8